an almost frictionless bearing consisting of two or more rollers on a flexible metal band, that serves as a suspension system in various devices, as switches, valves, pumps, etc.
See rolamite in American Heritage Dictionary 4
(rōˈlə-mītˌ)
noun
A mechanism consisting of two or more hard cylindrical rollers with a flexible nonstretching band looped around them, so that the rollers move against each other with very little friction.
(click for a larger image)
rolamite
When rotated as indicated in the top illustration, the rollers and metal strip will move to the right.